A Comprehensive Review of Microalgae Biochar for Pharmaceutical Wastewater Remediation

ABSTRACT Pharmaceutical residues are increasingly detected in wastewater, posing health, and ecological threats. Conventional wastewater treatment methods are ineffective against emerging contaminants, necessitating the development of alternative, sustainable adsorbents with higher removal efficiency. Biochar, a carbonaceous material synthesized from thermochemical degradation of biomass with tunable surface chemistry, is a promising option. Microalgae offer distinct advantages, such as exceptional photosynthetic efficiency, the ability to accumulate lipids & carbohydrates, and adaptability. It has demonstrated enormous potential as a feedstock for biochar production, as it can be cultivated on non‐arable land, using wastewater or saline water. The chemistry of microalgae biochar (MAB) makes it uniquely suitable for removing pharmaceutical waste because it combines nitrogen doping, oxygenated groups, phosphate sites, and mineral oxides not common in conventional biochars, enabling removal through a variety of interactions, such as hydrogen bonding, π–π stacking, ion exchange, and metal complexation. Despite the many advantages, studies on MAB for contaminant removal remain fragmented, limited to batch adsorption, and lack mechanistic certainty. Standardized protocols, regeneration data and real wastewater applications are underexplored. This review consolidates scattered evidence on MAB and links its unique chemistry to pharmaceutical removal pathways. It outlines research priorities for translating laboratory‐scale findings to scalable wastewater treatment solutions.